Elongate brush barriers are well known and are utilised in a wide variety of commercial, domestic and industrial applications. Elongate brushes are used extensively as draft seals around doorways and windows, light seals around doorways for dark rooms, automotive weather seals, and the like and may be used to seal out air, water, light, vermin, birds, sound, dust leaves, snow or the like. Elongate brushes are used as spray supressants around wheel arches of heavy vehicles. They are also used as sweeping or scrubbing brushes for road sweepers, car washes, food processing apparatus, cleaning brushes for conveyors and the like. They are used extensively as seals around aerobridges, scourers, spiral conveyors for fragile goods, electronic conductors, electromagnetic gasketting, just to name a few.
Conventional elongate brushes generally consist of a plurality of bristles retained in a rigid U-shaped metal channel. The bristles are generally folded about a retaining wire and a rigid steel strip is roll-formed into a U-shaped channel which clamps the bristles about a retaining wire. Whilst such rigid elongate brushes are useful for many applications, the finished product is very rigid and generally linear and it is difficult, expensive, or not possible to form into a different shape such as a circle, semi-circle, spiral or helix. Further the shape of the backing or base of the U-shape is limited to either square or rectangular, according to the dimensions of the flat steel stock used for the backing. In many applications where hygiene or corrosion resistance is important, the backing must be galvanised or stainless steel, which adds to the cost of production. When complicated brush products such as spirals, circles or the like are required, the backing often has to be welded or otherwise attached to a secondary carrier.
It would be desirable to provide for many applications an elongate brush which is flexible along its length so that the brush can be bent into any desired configuration. For example, to a helix for rotating cylinder sweepers, or conveyors, into a spiral for rotating disk sweepers, or simply being able to be directed along a guide, for example in a channel around door frames or the like where the brush is flexible enough to be fed along the guide off a spool.
There have been a number of attempts to manufacture a flexible elongate brush. One method involves the extrusion of a thermoplastic backing around the base of a line or bristles with the bases of the bristles being melded into the extruded backing using infra-red radiation or some similar heat source. Whilst the resultant elongate brush may be flexible to some extent, it suffers from a number of disadvantages. First, it is necessary for the extruded backing and bristles to be of a compatible material such that the backing will meld to and about the bristles when heated. This is acceptable when bristles made from propylene or polyethylene are used. Natural or heat sensitive bristles such as horse-hair or cotton will generally degrade at the temperatures necessary for co-extrusion with a backing. Moreover such fibres are not meldable with thermoplastic backing materials. Unless the melding of the bristles and backing is secure, bristles may readily fall away from the backing. Furthermore, it is necessary to keep the array of bristles in an orderly manner when the backing is applied. It may be necessary to keep the bristles orderly by providing sewn or woven retaining threads close to the base of the bristles which are to be melded. One other method involves the steps of knitting bristles into an orderly array, heating the bases of the bristles to melt them together along a central line, slitting the melted bristle bases to form two brushes, extruding a backing on each brush then cropping the bristle tips. Such a process, however, involves considerable work and hence adds to the cost of manufacturing such product without producing a superior product.
Whilst the problems associated with manufacture of flexible brushes have been discussed, similar problems exist in manufacture of flexible elongate "fin" type barriers such as blade wipers, squeegees or flexible blade-type seals. In such cases the problems associated with providing a flexible carrier exist, these problems being virtually identical to those faced with flexible elongate brushes.
Accordingly, there is a need to provide an elongate barrier which is flexible and which overcomes one or more of the problems of the prior art.